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Whats the options if you want to risk going no cats ?

how does it sound and does it need to be mapped ?

The catless downpipes on the supercharged B7 sounded un-be-<beep>-leiveable!!

In a cab, your ears will bleed!

For a c5 rs6 get it done asap map needed but sounds stunning ...........you will not regret it

Got a question also, about this in the B7 Rs4, Im thinking of taking the cats out because in SA, we dont have emissions laws and we have really bad fuel so taking out the cats could possibly release some HP!

My question is though would I lose power, because doesnt A high reving N/A engine need some sort of back pressure?

You would need to remap it to allow the ECU's to compensate for the lack of cats otherwise it will probably run rougher then OEM.

aka_dk wrote:Whats the options if you want to risk going no cats ?

how does it sound and does it need to be mapped ?

Hi i sold my RS4 at the beggining of the year - but i had decatted it before i sold it - oh and it also had a full Milltek non res and DMS remap and Gruppe M induction kit - I have no doubt that by decatting it i F###ED the ECU up - which went bang about a week after the DECAT - and god did it go bang - it was under full acceleration when power just completely cut - went into limp mode - could barely manage 20 MPH - teeth onto the steering wheel moment - I had it replaced and remapped and then sold it - but jesus it sounded amazing - pop bang crackle on lift off - dont decat - go for sports cats

I've got no cats on my supercharged b7 do it! It's the best noise you'll hear if you go on the srs forum in the events and gatherings section there's two videos off my car from the rr day listen to that then you'll go catless

stevomepy wrote:

aka_dk wrote:Whats the options if you want to risk going no cats ?

how does it sound and does it need to be mapped ?

Hi i sold my RS4 at the beggining of the year - but i had decatted it before i sold it - oh and it also had a full Milltek non res and DMS remap and Gruppe M induction kit - I have no doubt that by decatting it i F###ED the ECU up - which went bang about a week after the DECAT - and god did it go bang - it was under full acceleration when power just completely cut - went into limp mode - could barely manage 20 MPH - teeth onto the steering wheel moment - I had it replaced and remapped and then sold it - but jesus it sounded amazing - pop bang crackle on lift off - dont decat - go for sports cats

There is no feasible way the removal of your cats caused an ECU failure, the closest I can get to in my mind is the CPU working harder trying to compensate for the lack of cats in real time whilst driving, but even then it should be capable of running at full load with no issues, I think it is most likely that your ECU was about to fail anyway.

Surely the only thing that cats will impact is the post o2 sensor?

Exhaust gas flow and its rate from the engine? ECU tries to compensate for greater flow through engine by advancinfg fueling / timing to beyond parameters designed in the engine?

Are you saying removing cats its a step too far P G? Surely not just a step too far for a car that hasnt been custom mapped? My car runs with 2 of its lambda probes inop as part of the mrc map if you have sports high flow cats fitted

I'm catless (I've always had an allergic reaction to them anyway...make my eyes go all puffy) and it is AWESOME. Especially in this cold weather, it's loving it. The noise, oh boy, the noise!! As already mentioned, the popping and banging on the overun is superb too and the power is awesome. This is with one of Doug's 'finest range' of remaps of course. It's got to be done!!!!

Decatting will not cause damage. Because it is loud we now remove the retarded timing start procedure for cat warm up - so it starts a lot quieter and lower revs. Karl - next time yours is in we can update yours to do this.

Milltek make their downpipes with no cats - but don't advertise them as they are "motorsport use only". These mate straight up to stock catback or a milltek.

Cheers Doug
Will email for a quote

Whats the penatly for being caught catless ? just a fine?

a fine if caught, mot failure + might be seen as an insurance invalidating mod if undeclared